The SF-7 is based on the Texas Instruments INA138High-Side Measurement Current Shunt Monitor. It has a maximum input voltage of 36V and is designed to measure currents between 50mA and 500mA. It uses a 0.1-ohm sense resistor and has a transimpedance gain of 4V/A. An antialiasing filter of 15.4khz is placed after a unity gain buffer that feeds a Texas Instruments ADC121C027 12-bit analog to digital converter. There is one jumper that allows the user to select between three addresses. The ADC reference is connected to VDD so the resolution is based on the voltage applied to the device. It communicates using a 2-wire interface compatible with I2CTM which supports Standard (100kHz), Fast (400kHz),and High Speed (3.4MHz) Modes. It has an out of range alert flag readable as part of the conversion register.

When purchased, additional information will be emailed to you including a Bill of Materials, pdf Schematic, board and Microchip datasheets, Altium schematic, Altium schematic and PCB libraries, and example Arduino code.

The code has a simple user interface on the Serial Monitor that looks like this:

Current Sensor SF-7: Main Menu

• 1. Initialize Configuration Register
• 1. Get Configuration Register
• 1. Read Voltage
• 1. Get Lowest Conversion
• 1. Get Highest Conversion
• 1. Set Low Limit
• 1. Set High Limit
• 1. Set Hysteresis
• 1. Get Alert Status Register
• A. Get High Lim Register
• B. Get Low Lim Register
• C. Get Hysteresis Register
• D. Clear Alerts
• H. Help Menu